Fixed bug: Uncontrolled recursive calls that caused an infinite loop when loading certain pipelines containing Transformer2DModel (#11923)

* fix a bug about loop call

* fix a bug about loop call

* ruff format

---------

Co-authored-by: Álvaro Somoza <asomoza@users.noreply.github.com>

Author: lengmo1996

src/diffusers/configuration_utils.py

@@ -763,4 +763,7 @@ def from_config(cls, config: Union[FrozenDict, Dict[str, Any]] = None, return_un
         # resolve remapping
         remapped_class = _fetch_remapped_cls_from_config(config, cls)
 
-        return remapped_class.from_config(config, return_unused_kwargs, **kwargs)
+        if remapped_class is cls:
+            return super(LegacyConfigMixin, remapped_class).from_config(config, return_unused_kwargs, **kwargs)
+        else:
+            return remapped_class.from_config(config, return_unused_kwargs, **kwargs)

src/diffusers/models/modeling_utils.py

@@ -1877,4 +1877,9 @@ def from_pretrained(cls, pretrained_model_name_or_path: Optional[Union[str, os.P
         # resolve remapping
         remapped_class = _fetch_remapped_cls_from_config(config, cls)
 
-        return remapped_class.from_pretrained(pretrained_model_name_or_path, **kwargs_copy)
+        if remapped_class is cls:
+            return super(LegacyModelMixin, remapped_class).from_pretrained(
+                pretrained_model_name_or_path, **kwargs_copy
+            )
+        else:
+            return remapped_class.from_pretrained(pretrained_model_name_or_path, **kwargs_copy)